Three early transportation trends could xxx wepsoon transform the way global city dwellers get around, analysts say.

The switch to electric cars, use of car sharing services and the arrival of driverless vehicles are all expected to grow substantially by 2030 -- potentially making it cleaner and easier to navigate cities around the world, Bloomberg New Energy Finance (BNEF) said Tuesday in a new report.

"Vehicles and the way they are used will change more in the next two decades than they have in the last 100 years," said Colin McKerracher, BNEF's head of advanced transport in London.

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He said the declining costs of electric-car batteries and the rapid advance of connected technologies are key reasons for the transit transformation.

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BNEF and consulting firm McKinsey & Company looked at how these three developments could play out in 50 cities around the world. What they found is that the projections vary based on each city's demographics and existing transportation policies.

In some more densely populated cities, the analysts found electric cars would replace a large share of petroleum-powered cars. However, in more sprawling metro areas, they predicted a rise in self-driving cars.

Their study arrives as city leaders and urban planners are increasingly grappling with how to keep cities livable and accessible -- even as millions more people move into urban areas every year.

Original image has been replaced. Credit: Mashable

Around 66 percent of the global population is expected to live in urban areas by 2050, up from 54 percent of people today, the United Nations estimates.

That leaves cities with essentially two potential paths when it comes to transportation, according to the BNEF study and a separate report, also out Tuesday, by the Institute for Transportation Development and Policy (ITDP).

In one scenario, city dwellers would increasingly use ride-hailing and car-sharing apps to summon efficient, electric and probably self-driving vehicles. Extensive networks of public buses and trains would quickly whisk commuters to their destinations, and streets would be largely clear of congestion and smog.

In cities that follow the other pathways, however, streets would be clogged with traffic and tailpipe emissions. Public transit systems remain too slow or sporadic to reliably get commuters to work. Taxis, Ubers and personal cars -- autonomous or otherwise -- dominate the roads, guzzling mainly gasoline.

Vehicles stuck on the road during in Zhengzhou, China, Sept. 22, 2014. Credit: VCG via Getty Images

"There's a lot of room for [technology] to significantly benefit people moving around in cities, in terms of costs, environmental impacts and ease of transport," McKerracher told Mashable.

"But there are some pitfalls if we don't get it right," he said.

In other words, decisions made now are critical because they will lock in urban infrastructure for decades.

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Clean, shared and self-driving cars

As cities adopt more self-driving and shared vehicles, McKerracher said, streets could become more congested if residents don't take to carpooling or using public transportation as well. Smog and greenhouse gas emissions could rise if those cars run on petroleum instead of electricity, hydrogen or other fuel alternatives.

An Uber driverless Ford Fusion drives in Pittsburgh, Pennsylvania, Sept. 22, 2016. Credit: Jeff Swensen/Getty Images

BNEF found that in sprawling high-income suburbs, such as San Francisco or New York City's metro area, total passenger miles are projected to rise by 25 percent by 2030 compared to today's levels. One reason may be that suburbanites might ditch commuter trains or downtown-bound buses in favor of driverless cars.

Large cities in emerging economies will likely see a rise in car sharing services, such as Zipcar or car2go, the BNEF report found. In cities like Mumbai, Delhi and Mexico City, shared vehicles could account for nearly half of all passenger miles traveled as soon as 15 years from now.

But in densely populated, high-income cities, such as London and Singapore, electric vehicles are expected to represent as much as 60 percent of all cars on the road by 2030, thanks to policies that require or incentivize zero-emissions vehicles.

The electric-powered Go Ultra Low Nissan LEAF, left, and Kia Soul EV, right, charge on a London street. Credit: Getty Images for Go Ultra Low

London, for instance, will start requiring new taxis to be zero-emissions capable in January 2018.

"If done right, this can benefit the cost and environmental profile of moving around in cities," McKerracher said.

"But if left completely on its own, there's some potential negative outcomes as well."

Rapid public transportation

Public transportation will similarly struggle in coming years if city leaders don't expand and upgrade networks to accommodate more commuters, according to the Institute for Transportation Development and Policy (ITDP).

The New York-based nonprofit studied how today's public transportation systems -- not tomorrow's cars -- are shaping cities worldwide.

In the Tuesday report, ITDP looked at 26 major cities and their greater metro areas to determine how many residents lived within a short walking distance (0.62 miles, or 1 kilometer) of high-quality "rapid transit."

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"We found that in many cities around the world, the rapid transit system has not expanded commensurately with the cities' growth," Clayton Lane, CEO of ITDP, told Mashable.

"That's meant that a large portion of people in large cities don't have access to rapid transit, but also that the poor are disproportionately affected," he said by phone.

ITDP defines "rapid transit" in five ways. Systems should have: consistent, short distances between stops; good frequency; the option to pay bus fares before boarding; dedicated lanes for buses; and dedicated tracks for trains.

In New York -- both beloved and begrudged for its subway system -- about 77 percent of the city's 8.4 million residents have access to rapid transit. But if you factor in the city's sprawling metro area, then only 35 percent of the nearly 20 million residents can easily and quickly access public transportation.

One hundred percent of Parisians have access to rapid transit within the city, while in Los Angeles, São Paulo and Johannesburg, only about a quarter of residents do, ITDP said.

Passengers board a subway car in Tokyo, Japan. Credit: Junko Kimura/Getty Images

ITDP released its report ahead of Habitat III, a U.N. conference on cities held once every 20 years. The event in Quito, Ecuador next week will focus on how to develop "prosperous and equitable" cities for all residents -- including the 2.5 billion people expected to move into cities by 2050.

Lane said he hoped the ITDP scorecard would help city leaders better understand how to improve their mass transit systems.

"The way that cities are developed matters enormously, and it's why the next 20 years are so important," he said.

"With rapid urbanization, cities will be developing, and mayors have to make a choice: Will the city be compact and accessible, or will cities sprawl and require driving and be much less efficient?"